Underreamer



Allg. 9, 1938. C. SMITH v2,126,146

u UNDERREAMER Filed May 29, 1956 2 Sheets-Sheet l ATToe/VEK 2 sheets-sheet 2 H. C. SMITH UN DERREAMER Filed May 29, 1936 lAug. 9, 1938.

Patented Aug. 9, 1938 UNITED STATES PATENT OFFICE Application May 29,

6 Claims.

This invention relates to underreamers, and particularly to that class of underreamers operated by rotary apparatus.

The use of underreamers in the oil Well industry is Well understood, particularly where formation is to be cut a size larger than the drilling tool. The necessity for enlarging a Well hole results Where it is desired to cement back of a casing and also Where casing shoes are used which are, of necessity, larger than the drill.

An object of the present invention is to provide an underreamer wherein cutter members are readily collapsed out of casing engagement While the underreamer is being lowered through a casing, and then moved into formation engagement at the will of the operator, the operative control being at the surface of the Well hole.

Another object is the provision of an hydraulically controlled underreamer, the hydraulic control being such as to actuate positive mechanical means in turn directing cutter members of said underreamer into formation engagement.

Another object is the provision of an un-derreamer which may have the cutter elements thereof controlled from the surface of the well, hydraulically, and in such a manner that the diameter of the reamed hole may be varied.

Another object is the provision of an underreamer having few parts, simple of construction, positive in operation, which may be readily assembled and disassembled, Which permits any broken parts to be easily removed, and is generally superior to underreamers now known by the inventor.

Another object is the provision of an underreamer not dependent for operation upon the use of springs for expanding the cutters.

Another object is the provision of an underreamer which may be readily passed through a casing Without the cutters injuring the casing or in turn the casing injuring the cutters.

Other objects and uses of the invention will readily suggest themselves to those skilled in the art, and With the above set forth objects, including simplicity of structure, inexpensiveness in cost of manufacture, in View, the invention consists in the novel and useful provision, formation, construction, association, and relative arrangement of parts, members and features, all as shown in a certain embodiment in the accompanying drawings, described generally, and more particularly pointed out in the claims.

In the drawings:

Figure 1 is a fragmentary sectional View of a well hole Within which is received the improved 1936, Serial No. 82,484

(Cl. Z- 74) underreamer, the underreamer cutters being in formation engagement below the well casing,

Figure 2 is an enlarged fragmentary vertical sectional view of the underreamer Within Well casing,

Figure 3 is an enlarged fragmentary vertical sectional View, the underreamer cutters being below the lowermost end of the casing and in formation engagement,

Figure 4 is a sectional vieW on the line 4 4 of Figure 2,

Figurev 5 is a sectional View on the line 5-5 of Figure 3, and,

Figures 6 and 7 are sectional views on the lines I-Ii and 'I-'I of Figure 2.

Referring now With particularity to the drawings, the improved underreamer is designated as an entirety by the numeral I, and the same includes a body 2 which may be provided with a curved periphery and with a central bore 3 forming a Water course. The elongated central portion of the body may be of greater diameter than the end portions 4 and 5. The portion 4 may be formed with a pin, indicated by dotted lines at 6 in Figure 1, and with a box for the end 5, as indicated by dotted lines at 'l in Figure l. In this manner, the underreamer as an entirety may be suitably secured at one end to-a fishtail or other type of bit 8 having ports 9 communicating with the central bore 3 of the body, and the opposite end through the medium of a coupling I3, is secured to drill pipe I I. This drill pipe or string, in turn, communicates with the surface of the Well.

The said body is formed with one or more equidistantly spaced troughs opening outwardly of the periphery and, in the present instance, three troughs or grooves are provided, as illustrated in Figures 4 to 7, inclusive. For convenience, a trough Will be designated as I2. As is customary in trough formation, the bounding end walls I3 are curved from the. bottom I4 of the trough outwardly to the periphery of the body. Fitted Within both curved portions I3 and'I4 are blocks I5 and I6, the peripheries of which, as shown in Figure 4, are curved to form a continuation of the curved periphery of the body. These blocks are both provided with longitudina bores Il and I8 nd with transverse screw-threaded bores I9 and A shaft 2| is provided with portions of different diameters 22, 23 and 24, each'portion 23 and 24 being eccentric to the axis of the portion 22. Beyond the portion 24 is a further portion o1 the shaft 25, the axis of which lies within the axis 'of the portion 22. Adapted to be mounted upon the eccentric portions are cutter rollers 26, 21 and 28.

A bearing block 29 receives in part the portion 25 of the shaft, this bearing block being provided with a through bore for this purpose, as shown at 30. Interposed between the bearing block 29 and the roller 28 is means 3| comprising a sleeve having on its surface a helical thread 32. This sleeve is transversely bored, as shown at 33, and the portion 25 of the shaft is transversely bored whereby a pin 34 may pass through the bores of the sleeve and of the shaft for securing the said sleeve to the said shaft in such a manner that rotation of said sleeve will produce rotation Adapted to be interposed between the block I6 and thelowermost cutter roller 26 is a block 35 provided with a longitudinal bore`36 and with a transverse bore 31. shaft extends through a portion of the bore 36 and into the bore 31. Theend portion of the shaft where it'is received within the bore 31 is provided with an eccentric lever 38 forming by this construction a crank. Fitted withinY the bore 31 is a piston 39 provided with an arm 49 secured to the lever 38. This piston is received in part within the water course 3. The piston arm is swingingly mounted to the piston head in any suitable manner, such as by pinning, as illustrated in Figure 1 at 4I.

In order to hold the shaft, cutter rollers, and the like in position of assemblage to the blocks I5 and I6, I have provided balls, as illustrated at 42 and 43. The balls 42 and 43 are placed within the bores I1 and I8, and when the bearing block 29 has its bore 3U in alignment with the bore I1, the ball 42 will span the two bores but the ball will not completely enter the bore 30 for the reason that the bore 30 is of lesser diameter than the bore I1. A screw-threaded pin 44 is then placed in screw-threaded engagement with the bore I9 so that the ball is held in the position shown in Figure 2. The Same is true for the lower block in that the ball 43 will, in part, be received within the bores I8 and 36 when a threaded pin 45 is in threaded engage'- ment with the bore 29. In this manner, the several parts are locked within the trough of the body.

The operation, uses and advantages of the invention just described are as follows:

We assume that the underreamer is to be lowered within the well casing, forr the purpose of reaming out theV hole beneath the casing: The operator at the surface of the well may relieve the mud pressure through the drill string until such time as he desires to underream. Upon forcing mud under pressure through the drill string and the water course 3 of the underreamer body, pressure will be exerted for one operative unit against the piston 39 to force the same inwardly of the bore of the block 35. When this occurs, the shaft 2l will be rotated through the medium of the piston arm connection with the crank arm. As the cutter rollers are eccentrically mounted upon the shaft, rotation of the shaft will move the rollers from completely within the trough to outwardly thereof and beyond the periphery of the body of the underreamer. Viewing Figure 7,

it will be observed that the pistons are in such position as to be readily moved by any fluid passed through the course 3 ofthe body. This figure also illustrates the fact that the piston arms are so secured to the cranks of the shafts as to never be on dead center. When it is de- The portion 22 of the sired to come out of the well hole, the lowermost end of the casing, as shown at 46 in Figure 3, will engage the spiral thread 32 and rotate the sleeve 3I. This rotation of the sleeve will rotate the shaft due to the pin connection 34 between the shaft and the sleeve, and restore the cutter rollers within the trough, and out of casing engag'ement.

I have thus provided a device which does not depend upon springs for moving the cutters and one which may be readily assembled or disassembled, and to replace cutters which have been damaged.

I claim:

l. In an underreamer construction, a body formed with a central bore through which fluid is adap'ted to be passed, a rotatable shaft having a portion eccentric to its axis of rotation, an underreamer cutter mounted on the eccentric portion and adapted to be maintained within the body or projected beyond the periphery of said body due to said mounting when the shaft is rotated, and means connected to said shaft and exposed to the path of flow through said central bore to rotate said shaft.

2. In an underreamer construction, a body formed with a central bore through which fluid is adapted to be passed, a rotatable shaft hav ing a portion eccentric to its axis of rotation, an underreamer cutter mounted on the eccentric portion and adapted to be maintained within the body or projected beyond the periphery of said body due to said mounting when the shaft is ro tated, and a piston eccentrically secured to said shaft and in part positioned in the path of uid flow through the central bore of said body.

3. In an underreamer construction, a body formed with a central bore through which uid is adapted to be passed, a rotatable shaft having a portion' eccentric to its axis of rotation, an underreamer cutter mounted on the eccentric portion and adapted to be maintained within the body or projected beyond the periphery of said body due to said mounting when the shaft is rotated, means connected to said shaft and exposed to the path of flow through said central bore for rotating said shaft to project said underreamer cutter outwardly beyond the periphery of said body, and means for rotating said shaft to retract said projected cutter Within the periphery of said body.

4. In an underreamer construction, a body formed with a central bore through which fluid is adapted to be passed, a rotatable shaft having a portion eccentric to its axis of rotation, an underreamer cutter mounted on the eccentric portion, and adapted to be maintained within the body or projected beyond the periphery of said body due to said mounting when the shaft is rotated, means connected to said shaft and exposed to the path of flow' through said central bore for rotating said shaft to project said underreamer cutter outwardly beyond the periphery of said body, and a sleeve on said shaft formed with a spiral thread for engaging the lower end of the Well casing, when said body is-elevated in the well, for rotating said shaft to retract said underreamer cutter within the periphery of said body.

'5. In an underreamer construction, a body formed with a central bore through which fluid is adapted to be passed, a rotatable shaft having a portion eccentric to its axis of rotation, anl underreamer cutter mounted on the eccentric portion, and adapted to be maintained within the body or projected beyond the periphery of said body due to said mounting when the shaft is rotated, means connected to said shaft and exposed to the path of fiow through said central bore for rotating said shaft to project said underreamer cutter outwardly beyond the periphery of said body, and means for engaging the lower end of the Well casing, when said body is elevated in the Well, for rotating said shaft to retract said underreamer cutter within the periphery of said body.

6. In an underreamer construction, a body formed with a groove in its periphery, a block secured in each end of said groove, a, ball tted in a bore in each of said blocks, bearing blocks` tted in said groove adjacent said first blocks,

respectively, each of said bearing blocks being provided with a bore of smaller diameter than the ball, in the block adjacent said bearing block, to receive a part of said ball, to lock said bearing blocks in position in said groove, means for detachably holding said balls in locking position in said blocks, a shaft having a portion eccentric to its axis of rotation journaled in said bearing blocks, an underreamer cutter mounted on the eccentric portion of said shaft, means for rotating said shaft to project said cutter beyond the periphery of said body into underreaming position, and means for rotating said shaft, when said body isrelevated, to retract said. cutter Within the periphery of said body.

` HERMAN C. SMITH. 

